The technology of the present disclosure relates to an image forming apparatus of an intermediate transfer system.
Conventionally, there has been known an image forming apparatus of an intermediate transfer system in which a toner image formed on a peripheral surface of a photosensitive drum is transferred to an intermediate transfer belt by a primary transfer roller and then is transferred to a recording paper by a second transfer roller. The intermediate transfer belt is rotationally driven by a driving roller abutting an inner peripheral surface thereof. The aforementioned toner image is formed on an outer peripheral surface of the intermediate transfer belt. In this type of image forming apparatus, a density correction unit for correcting image density may be provided. The density correction unit forms a test image for density adjustment on the outer peripheral surface of the intermediate transfer belt and adjusts a developing bias based on the density of the test image detected by a density detection sensor, thereby correcting image density. The density detection sensor is arranged at a radial outside of the intermediate transfer belt. A positioning member is provided at a position facing the density detection sensor while the intermediate transfer belt is held between the density detection sensor and the positioning member. The positioning member abuts the inner peripheral surface of the intermediate transfer belt, thereby performing the positioning of the intermediate transfer belt with respect to the density detection sensor. In this way, the detection accuracy of image density by the density detection sensor is improved.